A little diversion, but on topic from the OP. I'll respond to Opie's comments later. More sooner than later.
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three months ago I bought 200+ feet of white hollow single braided UHMWPE Spectra (tm) cord on ebay, maybe from an amateur rocketeer, because he was also selling Kevlar (highly temperature resistant) line, too, calling it "shock cord." This molecule and fiber is from the same family as Amsteel.
The Spectra was listed as 1/8" with a breaking strength of 1500 lb.
When the cord arrived, and very promptly, I thought it too thin and too light to be 1/8". I had 1/8" Amsteel on hand for comparison, another UHMWPE-based cord, rated at 2500 lb or so.
Well the Spectra is a dream to splice, opening its braids to easily pass a 6mm needle (No. 10), maybe 8mm as easily. Very soft, too. But, with a weight of no more than 7oz for 200+ feet, there was no way this could be 1500 lb breaking strength cord. I told the vendor. He repaid the money in full, accepted without comment my paypal re-payment to him pro-rata for what he did not want returned, and continued to list this and other cord, but with slightly reduced claimed strength.
I just bought more 1/8" cord from the same seller, again likely NOS, for interest. It is all Vectran, a strong synthetic fiber still made into high performance rope by New England Rope, Samson, and others, into composites, and into bowstrings too, among other uses.
Vectran tolerates elevated temperatures better than most Dyneema-likes, and has lower creep. NE Ropes offers two lines of Vectran hollow braid, V100 (tm) and V12. The specification sheets show breaking strength to be a strict and tight linear function of weight of the line, with weight and tensile strength listed for each of several nominal diameters, the smallest of which is for 1/8" V12. (Go ahead and divide numbers in column 5 and 6 by those in columns 3 and 4 for several sizes.The ratios will vary +- 5%, some of which is rounding error.)
KEY: lb/100= lb weight per 100ft of rope
g/m = gram weight per meter of rope
lbs = tensile strength in pound
kg = " " in kilograms
Weight ............................. ............. Tensile
...........................lbs/100' g/m...............lbs.......kg
1/8" ( 3mm)............ 0.5 7.4.......... 2,100.... 955
5/32 ( 4mm)........... 1.0 14.9........ 3,300.... 1,495
3/16" ( 5mm).......... 1.2 17.9........ 4,950.... 2,245
1/4" ( 6mm)............ 1.8 26.8........ 7,200.... 3,265
5/16" ( 8mm).......... 3.2 47.6........ 10,900... 4,945
3/8" (10mm)........... 4.8 71.4........ 17,000... 7,715
7/16" (11mm).......... 5.5 81.8........ 26,000... 11,795
1/2" (12mm)........... 6.6 98.2........ 29,200 13,250
http://neropes.com/product.aspx?mid=...6C&lid=1&pid=5
V12 tensile strength in lb = (approx) 275 to 298 times cordage weight (in grams per meter. (Call it 300 and de-rate by 10% afterward)
Now: The line I received weighs an estimated:
3.6 oz for 115 feet
= 3.1 oz per 100 feet
= 88 grams per 100 feet
=88 g per 30.48 meters
=2.9 g per meter
Consulting the New England Ropes chart, their 1/8" hollow-braid all Vectran V12 cord weighs
7.4 g / meter
Its listed tensile strength is
2100 lb, plenty to safely hang from
But, I weighed and estimate the Vectran I received at just 2.9 g per meter. That is about 40% the weight of the 1/8" NE Ropes V12. There is either some extraordinary exception to the functional relationship in the NE Ropes tables for Vectran V12 or what I have has an estimated tensile strength of:
2.9 / 7.4 X 2100
or 285 x 2.9
which comes to about:
825 lb. not 2100 lbs.
Now, that's OK by me, but it is not enough to suspend someone else in a hammock from. The price, delivered, was just $10 for 100+ feet. I get to play with Vectran, I might use it as a sheath. I also got to see how one vendor responded to the challenge that he mis-described the cord he was selling: He just keeps selling it.
BTW: Grizz at one point expressed dissatisfaction with Vectran for reasons that don't matter here. So far, I like that it is not fuzzy and soft at all, like the Allied Chemical Spectra. It is somewhat "springy." Maybe I'll use it to encase the Spectra in a hybrid soft shackle with greater strength. Or into low-creep whoopies.
I will tell the vendor, who ships very fast, how the weight of his 1/8" compares to the weight of a major mfg product.
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